The invention relates generally to the field of water sampling and more particularly to a periphyton sampler for water quality monitoring.
For many years periphyton samplers have been used as a research tool especially by aquatic biologists. In recent years, however, with the enactment of laws relating to water quality, periphyton samplers have been used for routine evaluation as well as long-term monitoring by government biologists and others. These samplers permit investigators to monitor water quality, identify polluted water and also locate water pollution sources.
Prior art samplers generally take the form of a floating rack for holding a plurality of glass microscope slides at a position just below the surface of the water being monitored. The sampler is placed in a stream, reservoir or lake and secured by a line to some anchor so the sampler will remain substantially stationary. The sampler is left in place for approximately two weeks during which time biological growth, usually in the form of algae, appears on the slides. At the end of the two week period, the sampler and slides are removed so that the biological growth on the slides can be identified and counted. From this information, water quality can be monitored.
Prior art periphyton samplers have generally been very expensive, custom made devices. For example, one typical prior art periphyton samplers has been made of plexiglass with Styrofoam floats. This sampler required a large number of plexiglass parts which were either screwed or cemented together, thereby contributing to high assembly labor cost. The screws were generally made of brass, thereby increasing parts cost.
Another failure of typical prior art periphyton samplers is that the floats are not easily replaced and can become eroded especially where the sampler is used in bodies of water frequently having chemical spills. For example, Styrofoam floats have been known to disintegrate after having come in contact with a gasoline spill.
Capsizing is another frequently encountered problem with known periphyton samplers. Often, wave action has a tendency to turn the sampler over, thus exposing the slides to the air and direct sunlight thereby killing the biological growth on the slides. If the sampler does capsize and expose the slides during a testing period, the test results are dramatically affected thereby giving rise to unreliable water quality monitoring.
A further problem frequently occurring with prior art periphyton samplers is that of vandalism. Since the devices must be anchored in water for a period of approximately two weeks and because the floatation members cause the sampler to be easily seen, they are easily discovered and often tampered with by boatmen, swimmers and others passing by. As such, the accuracy of the tests made with known samplers is subject to question.
A further disadvantage of known periphyton samplers is the relative difficulty in inserting and removing slides from the sampler. Known samplers have had slide holders permanently attached to or supported by floatation members thereby requiring on site loading and unloading, which is time consuming, or requiring used samplers to be completely replaced by another sampler and the slides removed from the first and used sampler when it is returned to the testing laboratory. This approach is costly and inefficient.
In view of the foregoing difficulties with known periphyton samplers for water quality monitoring, it is the primary objective of the present invention to provide a periphyton sampler which is capsize-proof so that the test results from water quality monitoring will be accurate.
It is still a further objective of the invention to provide a periphyton sampler for water quality monitoring that has a low profile in use so as to make the sampler difficult to be seen by boatmen, swimmers and other passersby, thereby reducing the likelihood of vandalism.
It is still another objective of the invention to provide a periphyton sampler for water quality monitoring in which slides are quickly and easily removed and replaced.
It is yet a further objective of the invention to provide a periphyton sampler for water quality monitoring which is shaped as well as being made in part with transparent materials so that the slides, in use, will not be shaded by the sampler itself so that the effect of sunlight on biological growth on the entire surface of each slide during a test can be substantially equalized.
It is still another objective of the invention to provide a periphyton sampler for water quality monitoring which can be manufactured and assembled quickly and inexpensively.